Installing Vapour Barrier, Warm Roof Insulation and a Greasy Sandwich

Hi, welcome to MR A BUILDERS! In this episode, we make significant progress on our house build by completing the diminishing battens, allowing us to start the plywood decking for the warm roof. We'll take you through the installation of the vapour barrier before fitting the 150mm insulation layer. Once that’s in place, we secure the top plywood deck using thermally efficient fixings. Plus, we’re already thinking ahead to the roof light upstand, prepping everything for the machining and installation of the timber structure in the next episode. If you're following along with our DIY house build, you won’t want to miss this important stage as we continue to make strides on the roof! Make sure to like, comment, and subscribe to MR A BUILDERS for more updates on this project and future episodes! Don’t forget to turn on notifications so you never miss a new video. Thanks for watching!
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[@lazylad8544]

Nice of you and matt to have a sit down sandwich at the end, you was only missing a candle and it would of almost been romantic 😂😂. Enjoying the videos keep em coming. 👍👍

[@Mr_A_Builders]

😂👍🏻

[@thomasanstiss469]

Lady and the ??????

[@Mr_A_Builders]

I didn’t see any spaghetti Thomas it was a bacon and sausage sandwich 😁👍🏻

[@damiencurran856]

Really like the videos lad was in the building game for 30 years. Now I'm working as a truck driver the videos keep me going on days when I'm missing the fun on the site.

[@Stormin_Mike]

I started watching you via the basement build and now watching this unfold. Unlike maybe some I'm watching on a Sunday evening and I must say I commend the choice of music (apart from the cornet), the editing and also pace is also quite therapeutic and relaxing....great.

[@TheNorthernmunky]

Excellent work as always Rich, wouldn’t expect anything less from ya mate.

[@proud_to_be_a_ted]

Good video.. overloaded my mind with all the information all in one go but i know why it has to be like that, if you took your time to explain we'd be here all night. Very very informative. Nice tight job chaps

[@GRAYZOGRAY]

brilliant work lads. love to see workers take pride in their work. nice clean and tidy job keep up the great work

[@ianb9103]

Great work again, guys. Building inspector just needs to watch your videos to see a professional team going above and beyond.

[@andrewoleary9704]

Another excellent episode guys 👍😀

[@therealdojj]

Back in the regular time slot 👍

[@paulf2529]

Good progress this week. The IIlbruck pu timber gun adhesive is an excellent product.

[@petel5560]

Great attention to detail. Thanks for sharing.

[@dublinsnob3989]

Job's a Goodin mate!

[@jimmy4952005]

top job well done boys 👍👍👍👍

[@ChrisJay]

Great Job

[@porkpie2884]

I love drywall screws. I use them for loads of things

[@robertmorris5214]

Great video guy's

[@davidharding3058]

Evening lad's top video as usual. 4inch block 4inch cavity 4 inch block . 75mm celetex in the cavity 25mm air movement gap how come your cavity is full with no air movement gap. Its mind blowing how things change from county to county across the UK. 😵‍💫🏴󠁧󠁢󠁷󠁬󠁳󠁿🍻👍🤷‍♂️

[@Mr_A_Builders]

It’s a 150mm cavity using cavity bats on this job but yes you can use a 75mm celotex instead and go for a standard 100mm cavity instead

[@Giant.Iain171]

It doesn’t, or at least shouldn’t, change area to area, but is completely dependent on wall construction and products used. Dot and dab or wet plastering internally, type of block work used, external finish, and most importantly type and brand of insulation used all affect the insulation needed. Standard celotex (the brand rather than generically meaning PIR) requires 50mm clear cavity, and 75mm almost certainly wont meet the 2022 part L requirements unless also insulating internally. There is a big knowledge and skills gap generally for insulation installation, we should get away from thinking generally, follow the plans and manufacturers u value calculators & installation guides.

[@leeedwards9994]

nice work fellas ......

[@DICEGEORGE]

I went on the one day EPDM course at Alfreton Derbyshire Permaroof

[@daveedwards3658]

Personally I would have used ply for the first deck

[@Mr_A_Builders]

And not OSB?

[@pauld3638]

Proper job.

[@handle1196]

How was the pir fixed down? Just by weight until the top deck and fixings went through?

[@sygad1]

I thought the vapour barrier had to come up against the insulation on all sides, not just the rear, is that not the case?

[@zakkychan123]

Excellent video pal. Do you have any tips to help mark out the joists so when screwing down the top deck you fix into a joist rather than the bottom sheet of (osb)? Cheers

[@ChrisNahvi]

What was the length of your red thermal break fixing? I’m currently about to start my own warm roof soon on my extension. Many thanks. Great video.

[@johnaward-q4k]

Can I ask what size Osb board you use straight on to your joists, great video.

[@ir7868]

Brilliant video but I’m very confused who you believe first comment( DL VULPES) or you. Please explain. Thanks

[@Mr_A_Builders]

I'm not sure what that comment said?

[@coulsyjoinery]

Try to avoid the cold bridge you created with the base layer osb. Also kerb upstands should have no cold bridge too. It makes for a really wide upstands unfortunately, but no cold bridge means no condensation.

[@Mr_A_Builders]

Your going to have to forgive me on this one but I can’t see the cold bridging issue with the base layer OSB as it’s not been penetrated into the warm space and also the up stands have to be made to the specification of the roof window ie. a certain width which means you can’t make an upstand to suit yourself.

[@coulsyjoinery]

@@Mr_A_Builders Hi, basically you took the warm side ie the base osb straight through to pick up the PIR on the external brickwork, which is the cold side. If you had stopped it at cavity and PIR down into cavity, there's no cold bridge. Then you frame the cold side to pick up the top osb and facsia. Yes kerbs can be difficult, but at the end of the day any physical connection other than insulation from inside to out is a cold bridge. Without seeing the roof light spec it's not so easy but there is usually a way. It's a bit like when brickies butt up to a existing structure and don't cut a cavity to follow suit. The cold wall just follows through making the cold bridge.

[@terrymorton9941]

What vapour barrier is that.... is it similar to alutrix, even that isnt self adhesive cheers..... great job.

[@Mr_A_Builders]

I can’t remember Terry sorry but yes it’s similar to Alutrix with a sticky back 👍🏻

[@terrymorton9941]

@@Mr_A_Builders thanks kid from memory its alutrix 600 or summat too much to remember nice work cheers

[@amazing451]

When fixing down the OSB board do you leave 2mm gaps in between for expansion ? Never seen done myself but I did once work with a company where the foreman told us to do it.

[@Mr_A_Builders]

The honest answer is no I didn’t mate and never have done. 👍🏻

[@EJ-ul1zs]

Any chance of the whole build cost of this extension? Realise this might be sensitive info but would be good to know for 2024/25 prices. Cheers.

[@Doggonewest]

Richie, what do you use to cut those 150mm insulation boards - I have tried a few different tools but always end up using an old wood saw - the end result is pretty awful! horrible stuff to work with! I Know Festool make a tool specially designed to cut this stuff but it is very expensive, and unless you are using this stuff everyday, the temptation is to use a handsaw, also - are you bringing the existing concrete roof up to the same level as the new roof? Regards nick

[@Mr_A_Builders]

Hi Nick I had a festool saw and sold it for the reason of using it enough. I use a sharp wood saw and just take it steady. However, I have also been using my table saw as well and flipping it over to run through twice. It works well with two people. I am doing the concrete roof yes but not the same level due to height of the window 👍🏻

[@Giant.Iain171]

I normally see builders use cross-firrings rather than diminishing battens. Are there benefits/drawbacks to either?

[@Mr_A_Builders]

Cross firrings don’t give you the same structural support to fix to in my opinion and using the battens as I did is very simple and they are still supported by the roof timbers. 👍🏻

[@Giant.Iain171]

@@Mr_A_Builders Great, thanks for replying, that’s what I thought. I suspect cross firrings is a lazy/easy way to do it; give the length and desired fall to the timber merchant and pick up pre-made firrings the next day.

[@13mowe]

Have a guess what dry wall screws are for !

[@BARTSHARPAirbrush]

Another great informative video, thanks guys. i've emailed you twice about a possible two storey extension but not had a reply and would really like you guys to provide a quote. Thanks, Tim Sharp

[@Mr_A_Builders]

Hi Tim I’ll check our emails but your name doesn’t ring a bell and I went through them yesterday again. Sorry about that and thanks for commenting. 👍🏻

[@tkthebear984]

You guys are cool dudes 👍 Really enjoying the series. Thanks guys 🙂

[@BARTSHARPAirbrush]

@@Mr_A_Builders thanks. Sent on 2nd and 8th Oct (if that helps). I'll forward again now.

[@ImtiazMohammad911-q5y]

Good job the wedge is called a furring

[@scottnever8732]

not using firings then?

[@gelleby3]

Why no overhang over the sides?

[@Mr_A_Builders]

There no need for soffit it’s a warm roof

[@gelleby3]

@@Mr_A_Builders Is it not nicer to have an overhang to provide cover against rain for both people and the side of the building?

[@Brown969]

Was thinking the same 👍 It looks like it's going to be rendered without any overhang. We'll have to wait and see 😉

[@briansutherland5414]

What different between putting insulation on top in between rafters

[@DICEGEORGE]

Steve roofer KZbin is the guru

[@DICEGEORGE]

Between rafters leaks moist air too much which condenses and rots the rafters

[@briansutherland5414]

​Thank you as find it funny done with insulation between rafters over 30 years ago still good just have good air circulation

[@DICEGEORGE]

@@briansutherland5414 yes, ventilation over the top makes it a 'cold roof', not ventilation is a 'warm roof' - steveroofer is an expert kzbin.info/www/bejne/gpSVdWiLaal9m9k

[@brianhannan2872]

Why do you call osb ply ?

[@Mr_A_Builders]

Turn of phrase Brian they are completely different

[@andypandy9931]

Don't they insist on cavity trays for an extension, I had to have them for my attached garage.

[@Brown969]

Depends on the Building Inspector. If the client or BI request them, the steel needs to be installed first. You can always use some type of fasade cream like Stormdry or Permoseal in place of a missing cavity tray.

[@rc3171]

No hardedge timber too fix your fascia’s too🤦🏻‍♂️

[@Mr_A_Builders]

Is OSB not good enough. I think it is

[@warflair1312]

Please mote it is the responsibility of the customer to ensure all products purchased and used are compliant with Building Regulations. Tell Infinity there is a spelling mistake on their technical drawing which will irritate the Spelling Polizie 😂

[@dlvulpes1048]

Ply/osb boards should not be put on top of warm roof.

[@Mr_A_Builders]

Oh here we go...go on then, I'll bite...I agree that ply is a no no but OSB on a warm deck roof, why not? I would like actual evidence in your answer, not just what you 'think' may happen.

[@dlvulpes1048]

Belive it or not, i think you will be pleased because you can skip the top boards. They will rot eventually as they are the dewpoint. They are not needed there. With the correct insulation, the roof material is bonded straight on to the insulation. I will find a link that shows the above.

[@dlvulpes1048]

kzbin.info/www/bejne/roi1fXaNotaHa5I

[@Mr_A_Builders]

@dlvulpes1048 I totally disagree as it's my understanding that people who believe this have a fundamental misunderstanding of where the dew point is. If you have the correct amount of insulation, correctly installed on top of a correctly installed top of the range vapour barrier (there's a lot of things to get right) then the dew point will be within the insulation, not on top. That's the whole point of a warm roof. Add to that that you can't GRP, amongst others, on insulation and the roof coverings that you can you will never be able to walk on that roof again with any confidence that it won't severely damage it. It's my opinion that no OSB on top will lead to more roof failures in time than having OSB.

[@gladiator5309]

You forgot to put the primer down before the VCL

[@Mr_A_Builders]

Does it need a primer with the VCL we used? Shall I answer that one? Yes? Ok then, the answer is no!

[@alanreeves459]

Makes me laugh to see you struggling to explain 😂 Get yourself a whiteboard to draw exaggerating drawings 😂

[@Mr_A_Builders]

Oh I see Alan you enjoy watching peoples pain 😂. The problem is trying to explain as simple as I can for people that know nothing. I get enough grief for talking too much already without introducing a white board and start adding drawings to my videos as well 😁👍🏻

[@matthewdrury7180]

It's OSB not ply.

[@Mr_A_Builders]

No it stands for Oriented strand board and it’s manufactured differently. That’s as much as I know about it 😂

[@davecass9486]

warm roofs suck,

[@Mr_A_Builders]

Bold statement Dave. Would you care to tell us why you think that seeing as they are a lot more efficient than a cold roof?